Diesel engines are known for their efficiency and durability, but when you’re talking about the 2020 Sierra 1500 pickup truck’s available 3.0L Duramax Turbo-Diesel engine, that’s just the beginning.
With up to 30 MPG highway† on 2WD models, 460 lb.-ft. of torque, 277 hp and a max towing capability of 9,000 lbs.†, the newest Duramax offers — everything truck owners want — capability, power and efficiency.
“The 3.0L Duramax was designed to be a ‘no excuses’ engine option that offers excellent fuel efficiency, great low-end torque and smooth responsive operation,” Assistant Chief Engineer John Barta states. “We delivered on those targets with outstanding fuel economy, best-in-class 277 horsepower† and great throttle response.”
Barta — a member of the team that created this new engine being built in Flint, Mich. — was there as it was developed and tested, and tested some more.
“We logged well over 2.5 million on-road miles specifically with the 3.0L Duramax,” Barta recalls. “More than five round-trips to the moon!”
To help test the durability, GMC seeks out nature’s extremes — going to Death Valley at the hottest times of the year, north to Canada at the coldest times of the year and to many of the highest elevations that a customer can drive in North America.
“In October 2018, our verification team drove eight development trucks to Fairbanks, Alaska, to find freezing temperatures and validate our diesel exhaust fluid systems prior to the upcoming winter season,” Barta says. “It was an epic 6,200-mile drive to Fairbanks from our Michigan Proving Grounds, and we found what we were looking for, minus 20 degrees Fahrenheit.”
The 3.0L Duramax diesel inline-six engine design lends itself to efficiency.
“The inline six is a naturally balanced engine,” Barta points out. “The result is we don’t need balance shafts and the engine only has one set of overhead cams (compared with two sets in a V6). Fewer parts mean less weight and friction and enhanced efficiency. It’s a win-win design that offers fuel economy and smooth operation.”
The 3.0L Duramax includes several new features that all work in harmony to increase power, reduce friction and increase efficiency.
Active Thermal Management targets specific areas of the powertrain system for heating and cooling. This not only helps the engine warm up quickly, but also maintains an ideal temperature for performance and minimizes fuel consumption. The system controls the coolant in new ways.
“Once warmed, it is able to pinpoint temperature levels at different locations in the engine to have optimum combustion. For instance, we can control the engine block and the engine head separately to maximize the effectiveness of the cooling system,” Barta explains.
“Also, new to the Duramax diesel engine family, the 3.0L uses a variable intake valve, we call it the swirl valve, to tumble or swirl the air at low rpm to get better combustion and power with less fuel.”
An electrically controlled, variable-geometry turbocharger moves the turbo blades to the desired position quickly, helping to enable responsive acceleration. In addition, a water charge air cooler cools the air from the turbo to increase air density and improve combustion and power.
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The 3.0L Duramax delivers its impressive torque at low rpm, perfectly suiting the engine for off-road use in the Sierra AT4.
“The 3.0L generates 95% of its torque at only 1250 rpm and full torque at 1500 rpm,” Barta tells us. “Paired with our 10-speed transmission, it provides great control without having to rev the engine to get over the rocks and out of the valleys. While climbing around on those rocks, the fuel consumption will be better. This will help allow longer treks and reduce the amount of fuel you need to carry.”